1. Field of the Invention
The present invention relates to a substrate processing apparatus for and a substrate processing method of executing processings on any of a variety of substrates such as a semiconductor wafer, a liquid-crystal-display-device glass substrate, a plasma-display glass substrate, an optical-disk substrate, a magnetic-disk substrate, a photomagnetic-disk substrate, a photomask substrate and the like.
2. Description of Related Art
In production of a semiconductor device or a liquid crystal display device, there is used a substrate processing apparatus for executing, on a substrate (semiconductor wafer or glass substrate), a variety of processings such as a plating processing, a resist coating processing, a cleaning processing and the like.
Such a substrate processing apparatus is formed for example by an indexer section in which a substrate is carried in/out from a cassette capable of housing a plurality of substrates, and a substrate processing section having a plurality of processing units, both sections being connected to each other.
The indexer section comprises (i) a cassette placing portion in which a plurality of cassettes can be placed as arranged in a predetermined cassette aligning direction, and (ii) an indexer robot linearly movable back and forth in the cassette aligning direction for carrying a substrate in/out from a cassette.
The substrate processing section comprises (i) a main transfer robot arranged to travel, for example, in a horizontal direction at a right angle to the cassette aligning direction, and (ii) a plurality of processing units disposed along the transfer passage of the main transfer robot. The main transfer robot has access to any of the processing units for carrying an unprocessed/processed substrate in/out from the processing unit.
An unprocessed substrate is taken out from a cassette placed in the cassette placing portion and transferred to the main transfer robot by the indexer robot. The main transfer robot is moved to a processing unit. First, the main transfer robot carries out a processed substrate from the processing unit and then carries the unprocessed substrate therein. While holding the substrate to which a series of processings have been completed, the main transfer robot is moved in the vicinity of the indexer section and transfers this processed substrate to the indexer robot. The indexer robot houses this processed substrate in a cassette.
The conventional substrate processing apparatus having the arrangement above-mentioned, is provided with two transfer robots, i.e., the indexer robot and the main transfer robot. This makes the apparatus complicated in arrangement, thus accordingly increasing the production cost thereof. Further if one of the two transfer robots gets out of order, any substrate cannot be processed. This is disadvantageous also in reliability.
Further, it is required to transfer a substrate between the indexer robot and the main transfer robot. This results in a variety of problems as follows.
For example, the main transfer robot and the indexer robot must be matched in operational timing. It becomes however complicated to program such that the two robots are operated in good timing.
Further, a substrate comes in contact with the respective substrate holding hands of the indexer robot and the main transfer robot, and there is an instance where a substrate is temporarily placed on a placing stand when transferring/receiving the substrate between the robots. This causes the substrate to repeatedly come in contact with a number of members. This accordingly increases the chances of particles occurring and attaching to the substrate. Thus, the substrate is disadvantageously easily contaminated.
Further, after a substrate has been transferred/received, the substrate is required to be positioned in the transfer robot which has received the substrate. At this time, the guide member on the holding hand and the substrate end face inevitably rub together, and the substrate holding hand and the substrate back face inevitably rub together. This disadvantageously generates particles to contaminate the substrate.